This article was published in the March 2012 issue of LEDs Magazine.
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At the inaugural Ecosystems in Solid State Lighting Conference in Washington, DC, last December, Dan Ruscheinski, vice president of sales and marketing at Carmanah, described an almost utopian lighting system of the future: one that is free of the grid, LED-based, adaptive and intelligent, more cost effective than today’s lighting systems. They are also secure and stable, environmentally friendly, and available to a greater proportion of the world’s population.
Indeed Makarand “Chips” Chipalkatti, senior director of SSL & emerging market initiatives for Osram Sylvania Inc., and one of the conference organizers, said the fulfillment of LED technology goes beyond the use of LED light source itself, and extends to the entire SSL ecosystem – the light source, power supply, controls, fixture, and any intelligence built into or used with the system, which makes SSL affordable and practical.
Intelligent office lighting
At the conference, Jim Brodrick, lighting program manager at the US Department of Energy (DOE), attempted to answer the question of “what might future lighting systems look like?” He chose the office environment to illustrate how the unique attributes of LED lighting might be used to save energy and money while enhancing the user experience. Brodrick explained that people are frustrated with the inflexible lighting systems of today. Often, lighting is not available when and where it is needed, and even simple lighting changes require rewiring above the ceiling level and the hiring of electricians. Also, users often end up paying high electricity rates when they use it the most – during the day.
Brodrick proposed a flexible lighting approach that is designed to use less energy than existing office lighting systems. This approach (Fig. 1) could involve mobile LED light heads on a track, which could be reconfigured wirelessly as needed, via smart phones or work stations. The system’s on-board batteries could be recharged during off-peak electricity hours.
The luminaires could incorporate daylight sensors and adjust light-output levels accordingly. Occupancy sensors could enable the luminaires to be turned off automatically when work areas are empty. The luminaires could be adjusted vertically or rotated to provide personalized, task-level lighting and prevent area over-lighting. “With this kind of an approach, we could see energy savings of around 40%,” said Brodrick. The rechargeable batteries could also eliminate the wiring along tracks and in the ceiling as well as typical power distribution issues. Brodrick concluded by asking attendees “Can it be done?” – challenging the lighting industry to think beyond the bulb in developing tomorrow’s LED lighting solutions.
Morgan emphasized that luminaires can be designed with many advanced capabilities such as integrated sensors for occupancy, daylight, temperature and energy, as well as control technologies (Fig. 2). He showed that smart luminaires can be used to build intelligent buildings. For instance, temperature sensing in real time has been used to identify problem areas in cold-storage facilities, such as insulation failures or excessively low or high temperatures that should be better regulated. “Right now, facility managers are mostly collecting data, but they can provide real-time energy management with the tools we have today,” he said.
Controls and dimming
Garrett Grega, senior manager of applied LED technology at Philips, also took up the topic of improved lighting control, stating that lighting in general is becoming more personal and more customizable. He referred to the potential of SSL to deliver addressable light, customized light and adaptable light based on personal needs or desired mood. In terms of wireless controls, he said that the technology is here today, so it is not a question of whether we will use addressable light technology, but when. He added that people may prefer to make lighting adjustments via gesture or voice rather than using a mobile device.
Russ MacAdam, director of commercial engineering development at Lutron Electronics, reviewed the challenges of dimming LED lamps and fixtures. He stated several of the benefits of dimming LEDs, including energy savings, improved ambiance and safety. In addition, LED component life can be lengthened by effectively lowering the operating temperature – potentially doubling or tripling the lumen-maintenance lifetime.
MacAdam noted that not all LED products are dimmable, and whether a lamp or luminaire is dimmable may only appear in the fine print on a package. He added that in the case of LED fixtures, different drivers are often available with different control options, including forward phase, reverse phase, three wire, 0-10V, DALI and DMX. The LED product’s signal and wiring must match the signal and wiring on the wall control. Lutron’s website provides a guide that matches control types with LED products.
The rise of SSL, along with other DC-based systems including solar energy panels and wind energy, has encouraged many parties to pursue a DC-based power grid, that eliminates inefficient DC/AC and AC/DC power conversions that waste energy. Brian Patterson, chairman of the EMerge Alliance, a member-funded association that promotes adoption of DC power distribution standards for commercial buildings, provided an update of the association’s activities at the conference. “With the new installations of solar and wind power and ramp-up of electrical vehicles on the market, an AC/DC hybrid coupled power network can consume up to 30% less energy, require 15% less capital and be 200% more reliable than existing systems,” he said.
Patterson talked about the Zero-Energy Commercial Building Consortium, which is looking into DC microgrids; these would eliminate AC/DC conversions at the equipment level, simplify equipment designs and layouts, provide improved interfaces with renewable energy sources and save energy. “Our vision is to foster more sustainable buildings by bringing hybrid AC-DC power architectures and DC microgrids to occupied spaces, data centers, building services, and outdoor applications,” he said.
Patterson explained that in current solar-powered facilities, the DC power generated by the photovoltaic cells is converted to AC at the appropriate level for use. If excess power needs to be fed back to the grid, it is reconverted from AC to DC. The Emerge Alliance proposes direct integration of DC energy sources, more efficient use of DC-based loads, and plug-and-play reconfigurability of electronics.
The EMerge Alliance, which currently has 80 members, is in the process of performing its first microgrid beta-site demonstrations. Fig. 5 shows a reconfigurable office space that utilizes DC-based solar energy to drive LED lighting and controls at Optima Engineering’s facility in Charlotte, NC. The installation uses free-floating acoustical ceiling clouds that distribute low-voltage DC power to light fixtures, sensors and other electronic devices. Lighting controls, including occupancy sensors and dimmers, were provided by Sensor Switch, an Acuity Brand, and Lithonia Lighting, also an Acuity Brand, provided the recessed and track lighting. The rooms can be easily reconfigured with minimal rewiring.
Ultimately, the EMerge Alliance would like to combine renewable energy, DC energy storage and system intelligence to enable net-zero-energy consumption for all new commercial buildings by 2030 and net-zero-energy consumption for all existing commercial buildings by 2050.
Carmanah’s Ruscheinski focused his talk on the adoption of solar-powered outdoor lighting systems, both street lights and signal lights, which his company manufactures. He said that the trend toward distributed energy capacity supports the adoption of solar-powered outdoor LED lighting.
Ruscheinski presented information based on a survey of North American municipal contractors and the reasons that non-users gave for not purchasing solar-powered street lights. The top reason was the uncertainty of battery life and the maintenance related to solar-powered lights. The second concern was a lack of industry standards and regulations. The third reason was related to cost and return on investment.
Ruscheinski called for continued cost reduction of solar street lights, improved industry education and standards work, and lobbying of governments and utilities for increased funding of solar-powered lighting systems. He believes that solar street lights offer a cost-effective alternative to grid-based street lights, particularly in developing countries where grids are either inaccessible or unreliable. He discussed the reliability of solar-powered systems, highlighting a case study where an earthquake struck Santiago, Chile, just three months following the installation of solar-powered street lights in a park. The park remained illuminated while the entire city lost grid power.